Which statement about the crankcase heater is true?

• A. It boils off liquid refrigerant trapped in the oil
• B. It cools the compressor oil
• C. It increases refrigerant charge
• D. It filters refrigerant

Answer: (A)

The crankcase heater’s job is to warm the compressor crankcase so any liquid refrigerant that has migrated into the oil can be boiled off and returned to the vapor space. This prevents refrigerant from diluting the oil and helps avoid slugging or lubrication problems when the compressor restarts. It doesn’t cool the oil, increase the refrigerant charge, or filter refrigerant, so those statements aren’t true.